The present invention relates to a linear ball guide assembly which by means of ball members bears a loading force and moment in all directions and achieves a smoothly linear movement along the straight guide rail at low frictional resistance. The linear ball guide assembly includes a pair of end caps formed with substantially U-shaped ball turning grooves for smoothing recirculation of the balls and facilitating manufacturing of the linear ball guide assembly.
The conventional linear ball bearings for accurately guiding a linear movement includes a linear ball bushing bearing and a linear ball guide assembly. Such bearing and guide assemblies have several loops of balls for bearing the load and guiding the movement at low frictional resistance. The balls are restricted within a recirculating path formed by grooves or holes for loaded and unloaded balls, and ball turning grooves. Ball retainers are used to prevent the balls from dropping out of the ball grooves when the slide block is separated from the rail.
The linear ball bushing bearing is mounted on a straight shaft or rail for bearing vertical or radial loads. Usually, the moment capacity thereof is lower than that of the linear ball guide assembly. The both sides of the guide rail of some linear ball guide assemblies and the corresponding inner sides of the slide block are formed with four rows of linear arched ball grooves to form four loops of balls for increasing the load and moment capacity thereof. The manufacturing technique for the linear ball guide assembly having four arched ball grooves is more complicated. To achieve an accurate position of four ball grooves and correct shapes thereof and insure the accuracy and smoothness of the recirculation of the balls on the guide assembly so as to even the load distribution over the four loops of balls, the manufacturing cost is increased. However, in fact, due to manufacturing tolerance, when the guide assembly suffers vertical load, only the upper two loops of balls bear the load, while the lower two loops of balls are free from the load. In addition, the contacting angles between the balls and the arch ball grooves will be affected by the load, so that the load is unable to be evenly distributed over the loops of balls. Therefore, the capacity of the guide assembly is lowered.
On the other hand, the loaded ball retainer of a conventional linear ball guide rail is made of a bent metal plate with a slot. When the loaded balls enter the ball turning grooves from the ball grooves, the end corner of the slot often presents an obstacle to the balls, and the rolling of the balls will be unsmooth and create noise.